Typical retail store refrigeration systems often utilize conventional fin-and-tube condenser coils to dissipate heat from refrigerant passing through the condenser coils. Usually, in large-scale retail store refrigeration systems, a singular, oftentimes large, conventional fin-and-tube condenser coil is sized to dissipate, or reject, an amount of heat equal to the heat load of the refrigeration system. In other words, the singular fin-and-tube condenser coil is sized to dissipate the amount of heat in the refrigerant that was absorbed in other portions of the refrigeration system.
Fin-and-tube condenser coils, such as those utilized in many retail store refrigeration systems, often display poor efficiencies in dissipating heat from the refrigerant passing through the coils. As a result, fin-and-tube condenser coils can be rather large for the amount of heat they can dissipate from the refrigerant. Further, the larger the condenser coil becomes, the more refrigerant used in the refrigeration system, thus effectively increasing potential damage to the environment by an accidental atmospheric release.
Usually, in large-scale retail store refrigeration systems, the single fin-and-tube condenser coil is positioned outside the retail store, such as on a rooftop, to allow heat transfer between the fin-and-tube condenser coil and the outside environment (i.e., to allow the heat in the refrigerant to dissipate into the outside environment). Further, a mechanical draft may be provided by a fan, for example, to air-cool the fin-and-tube condenser coil.
Another form of heat exchangers is the microchannel coil. Currently, the only major application of microchannel coils is in the automotive industry. In an example automotive application, microchannel coils may be used as a condenser and/or an evaporator in the air conditioning system of an automobile. A microchannel condenser coil, for example, in an automotive air conditioning system is typically located toward the front of the engine compartment, where space to mount the condenser coil is limited. Therefore, the microchannel condenser coil, which is much smaller than a conventional fin-and-tube condenser coil that would otherwise be used in the automotive air conditioning system, is a suitable fit for use in an automobile. Prior to the present invention, the microchannel condenser coil has not been used in retail store refrigeration systems, in part, because of the high costs and difficulty that would be associated with manufacturing a microchannel condenser coil large enough to accommodate the heat load of the refrigeration system.